This invention relates to a shredding and fluidization drying apparatus and, more particularly, to an apparatus for shredding a material such as waste paper or industrial waste in rotary drum assemblies and then fluidization drying the shredded material in a drying column with a hot blast upwardly fluidizing the material.
Many kinds of shredding and drying machines, including a fluidization drying apparatus, are known for shredding a material for recycling such as waste paper or industrial waste into fine particles or pieces and the shredded material with hot blast blown into a drying column.
With the drying apparatus of the type described above, the material introduced into the apparatus is liable to adhere to a material feeding portion or nearby because of the water content or viscosity of the material before the material is subjected to the drying treatment. The outer surface of the thus adhered and piled material may be burned when it comes in contact with a hot gas utilized as a heating medium for the drying treatment and, in a case where such adverse phenomenon has been continued for a long time, the burned material generates odors or, in an adverse case, the material may ignite and explode.
In the other case where the material introduced is in the form of cake or mixture of various kinds of components having densities different from each other, the components having heavy densities may be piled on the bottom of the drying column of the drying apparatus and the piled components will prevent the sufficient and stable feeding and circulation of the hot gas for drying the material.
Taking the above technical matters into consideration, the inventor of this application conceived a shredding and drying apparatus such as disclosed in the Japanese Patent Publication No. 60-9228 or Japanese Patent Laid-open Publication No. 61-291822. The shredding and drying apparatus disclosed includes a fluidization drying column or tower in which a pair of rotary drums provided with blade members are disposed for shredding a material and sucking hot gas for drying the material in a lower portion of the drying column. At the drying operation, the rotary drum is rotated to shred the components or parts of the material which are not upwardly fluidized with the ascending current in the drying column to effectively bring the material into contact with the hot gas as a heating source with the rotary drums rotating to evaporate the water content in the material and reduce the density thereof, whereby the shredded undried material can be easily dried in a short time and materials having components changed by the heat can also be effectively treated.
With the drying apparatus disclosed in the prior art publication, the hot blast is fed into one of the rotary drums at the axially central portion thereof and blown out through both the axial end openings. The hot blast blown from one of the rotary drums is induced into the other one of the rotary drums disposed with the material feeding side and the hot blast and the material sucked in the other rotary drum is then blasted upwardly from the axially central portion thereof. It may be desired to arrange the rotary drums so that the upwardly blasted material is effectively fluidized by the hot blast blown through both the ends of the rotary drum.
In order to achieve the functions or effects described above, according to the conventional technology, the rotary drum on the hot blast blowing side is provided with no blade member at the axially central portion of the rotary drum and the rotary drum on the material feeding side has a reduced length. According to this construction, however, the fed material is liable to stay in the space of the drying column by the hot blast blown from both the ends of the rotary drum and, in addition the material is liable to fall and accumulate in the space at both ends of the rotary drum on the material feeding side. These adverse phenomena prevent the effective fluidization of the material in the drying column and hinder the effective shredding or crushing of the fluidizing materials due to the mutual collision thereof during fluidization.
In another view point, in a case where the material to be treated includes foreign materials or components which cannot be shredded or crushed, for example, metallic parts or materials such as bolts or nuts, or stone or rock, these foreign materials will collide with the blades of the rotary drum and be sent flying. The foreign materials will then fall because of the heavy weight and again collide with the blade members. These phenomena will be repeated and a large noise due to the collision between the blade members and the foreign materials will be generated. In an adverse case, the blade members of the rotary drum may be damaged by the foreign materials intruded into the space between the rotary drum and the lower portion of the drying column or the rotary drum may itself be stopped. In such adverse cases, it is required to stop the operation of the drying apparatus and to remove the foreign materials. However, when the operation of the drying column is once stopped, all the material fluidizing therein falls due to its own weight and may be piled on the rotary drum. It is further troublesome for the operator to find and remove the foreign materials from the material piled on the rotary drum.